Mapping Aquifers From the Sky: California’s Statewide Airborne Electromagnetic Surveys
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o implement the Sustainable Groundwater Management Act (SGMA), local and state water managers need better information on groundwater. In response to that need, the California Department of Water Resources (DWR) is conducting airborne electromagnetic (AEM) surveys to map the subsurface beneath the state’s highand medium-priority groundwater basins. Irrigation Leader spoke with DWR’s Katherine Dlubac and Steven Springhorn about the surveys, which will help refine hydrogeologic models and identify potential areas for recharging groundwater. Irrigation Leader: Please tell us about your backgrounds and how you came to be in your current positions. Katherine Dlubac: I am an engineering geologist in the Technical Assistance Section within the Sustainable Groundwater Management Office at DWR. I’m also the project manager for DWR’s statewide AEM surveys. I hold bachelor’s and master’s degrees and a PhD in geophysics with a focus on using geophysical methods to characterize groundwater resources. After completing my graduate work at Stanford University, I went into private consulting and then started working with the California State Water Resources Control Board’s groundwater management program to support the implementation of SGMA. I then moved to DWR to work with Steven and the rest of the team to start up the statewide AEM surveying project. Steven Springhorn: I am a supervising engineering geologist at DWR. I am a program manager within DWR’s Sustainable Groundwater Management Office and lead our groundwater technical assistance activities. I hold undergraduate and master’s degrees in geology. In 2005, I took a job as a graduate student assistant at DWR, and I’ve been working on basin characterization and groundwater monitoring and management efforts at DWR ever since. Irrigation Leader: Please tell us about the general issues of groundwater and hydrogeology in the Central Valley.
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information about a specific spot, but it’s expensive to drill and collect that type of information. In addition, the boreholes are widely spaced, so you have to interpolate, and there is uncertainty about conditions between those points. This new technology, by contrast, gives us a continuous view of the subsurface. Irrigation Leader: When did DWR decide to conduct AEM surveying? Steven Springhorn: The passage of SGMA in 2014 created a paradigm shift in groundwater management. It sparked significant action in the groundwater community to work toward meeting its new requirements. One of DWR’s principal roles is providing technical assistance to local groundwater managers. When we asked them what they needed, they told us they needed better information about the subsurface. irrigationleadermagazine.com
PHOTO COURTESY OF DWR.
Steven Springhorn: Groundwater is a critical resource in California, especially in times of drought like right now. During droughts, up to 60 percent of the entire state’s water supply comes from groundwater. This underscores how important it is to understand and analyze groundwater basins across the state. We need to continue providing upto-date groundwater information to local and state agencies to help them manage groundwater sustainably. In the past, information about groundwater was gathered by drilling boreholes in various locations. That can provide good
A helicopter with AEM equipment, seen here at a DWR event in Acampo in San Joaquin County.
